共查询到20条相似文献,搜索用时 703 毫秒
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《New Astronomy》2020
A dozen of new precise times of eclipses were measured for the eclipsing binary DX Cygni as a part of our long-term observational project for studying neglected eclipsing binaries with a short orbital period. Based on a current diagram, we found for the first time that its period is increasing ( day/years) and that times of minima show also significant cyclical changes with a period of about 16 years, caused very probably by a third body orbiting the eclipsing pair. The minimal mass of this companion is 0.49 M⊙. The light curve solution in Phoebe results to the typical Algol-type semidetached configuration where the secondary fills its Roche lobe. The temperature of primary component was fixed to K according to its spectral type, which gives us K for the secondary. The photometric mass ratio was estimated . We also compare orbital parameters of selected known Algol-type eclipsing binaries with proven mass transfer and a third body. 相似文献
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《New Astronomy》2021
The present study deals with a Tsallis holographic dark energy model in a flat Friedmann-Lamatire-Rbertson-Walker space-time geometry in the context of higher derivative theory of gravity. We have solved the field equations by applying energy conservation-law in non-interacting case and have obtained such a scale factor where is called as model parameter which shows transit phase evolution of the universe (decelerating to accelerating). Using this scale factor we have obtained the various cosmological parameters viz. Hubble parameter , deceleration parameter (DP) , jerk , snap , lerk and max-out . Constraining on Hubble parameters by the observational data of we have obtained the present values of , and and by using these constrained values, we have studied other cosmological parameters. Taking the constant equation of state (EoS) for ordinary matter, we have investigated the effective behaviour of various cosmological parameters and energy conditions in our model. We have observed the present values of and discussed with CDM model. We have found the age of the present universe Gyrs, present value of DP and transition point which are compatible with several observational results. 相似文献
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《New Astronomy》2022
Detailed photometric analysis of V523 And and V543 And from the Wide Angle Search for Planets survey is presented for the first time. It was found that while V523 And is a detached binary, V543 And is a semi-detached binary star system. The adopted masses and radii for the primary and secondary components are M, R and M, R for V523 And; and M, R and M, R for V543 And. Orbital period variations of the systems were analyzed using the O-C method. The O-C change of V523 And is discussed in terms of the magnetic activity cycle of one or both components and light travel time effect (LTTE) due to a third body in the system. Among these mechanisms, LTTE seems to be the most appropriate mechanism to explain the O-C variation of the system since the quadrupole moments of the primary and secondary components () were found to be in the order of g cm. The O-C diagram of V543 And shows a downward parabolic trend, which suggests a secular period decrease with a rate of s/year. The parabolic O-C variation of V543 And was interpreted in terms of the non-conservative mass transfer mechanism. According to this scenario, the range of possible values of the mass gain rate () of the primary component of V543 And as well as the mass-loss rate () of the system were found to be – M/year and – M/year, respectively. 相似文献
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《New Astronomy》2024
In this work, a new static, non-singular, spherically symmetric fluid model has been obtained in the background of gravity. Here we consider the isotropic metric potentials of Durgapal-IV (Durgapal, 1982) solution as input to handle the Einstein field equations in environment. For different coupling parameter values of , graphical representations of the physical parameters have been demonstrated to describe the analytical results more clearly. It should be highlighted that the results of General Relativity (GR) are given by . With the use of both analytical discussion and graphical illustrations, a thorough comparison of our results with the GR outcomes is also covered. The numerical values of the various physical attributes have been given for various coupling parameter values in order to discuss the impact of this parameter. Here we apply our solution by considering the compact star candidate LMC X-4 (Rawls et al., 2011) with mass and radius km. respectively, to analyze both analytically and graphically. To confirm the physical acceptance of our model, we discuss certain physical properties of our obtained solution such as energy conditions, causality, hydrostatic equilibrium through a modified Tolman–Oppenheimer–Volkoff (TOV) conservation equation, pressure–density ratio, etc. Also, our solution is well-behaved and free from any singularity at the center. From our present study, it is observed that all of our obtained results fall within the physically admissible regime, indicating the viability of our model. 相似文献
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